Name:
Date:
Student Exploration: Covalent Bonds
Directions: Follow the instructions to go through the simulation. Respond to the questions and
prompts in the orange boxes.
Vocabulary: covalent bond, diatomic molecule, Lewis diagram, molecule, noble gases, nonmetal, octet rule,
shell, valence, valence electron
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
1. There are eight markers in a full set, but Flora and Frank each only have seven markers. Flora is missing
the red marker, and Frank is missing the blue marker.
What can they do so that each has a full set of markers?
Frank can find the blue marker
Flora can find the red marker
2. Otto and Olivia each have six markers. Otto is missing the purple and green markers, and Olivia is missing
the black and brown markers. What can they do so that each has a full set?
Otto can find the purple and green markers
Olivia can find the black and brown markers
Gizmo Warm-up
Just like the students described above, nonmetal atoms can share
electrons.As you will see in the Covalent Bonds Gizmo, atoms form
bonds in this way.
To begin, check that Fluorine is selected from the Select a
substance menu. Click Play ( ) to see the electrons orbiting the
nucleus of each atom.
1. The outermost electrons in each atom are called valence electrons. How many valence electrons does
each fluorine atom have?
2. Click Pause (
What happens?
7
). Drag a valence electron from the left atom to the right atom. Click Play.
They share a valence electron
3. Click Pause, drag a valence electron from the right atom to the left, and then click Play.
What happens now?
They share two valence electrons
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Activity A:
Get the Gizmo ready:
Sharing electrons
● Click Reset.
● Select Hydrogen.
Introduction: The electrons that orbit the nucleus of an atom are arranged into shells. The first shell contains
up to two electrons and the second contains up to eight electrons. Most elements are stable when they have
eight valence electrons—a rule of thumb known as the octet rule. (Elements with less than five electrons are
stable with two valence electrons.)
Question: What happens when atoms share electrons?
1. Predict: Each hydrogen atom has one valence electron, but it needs two electrons to be stable. How can
both hydrogen atoms each achieve a stable configuration?
Combine 2 hydrogen atoms
2. Form a bond: Drag the electrons so that they move around both hydrogen atoms. Click Play to observe
them in orbit, and then click Check. You have created a covalent bond.
� Congratulations, you have completed a molecule of hydrogen! Because the molecule has two atoms, it
is a diatomic molecule. Click the camera ( ) icon to take a snapshot of your completed molecule. Rightclick the image, and click Copy Image. Paste the image into the document below and label the image “H2.”
�
3. ✏️ Draw a diagram: Covalent bonds are shown in Lewis diagrams. In a Lewis diagram, dots represent
unshared valence electrons and dashes represent pairs of shared electrons.
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✏️ Hand draw in this space or click here to select EDIT to use the drawing tool.
Turn on Show Lewis diagram. What is the Lewis diagram for hydrogen, H2?
H
H
4. � Form a bond: Select Fluorine and turn on Highlight shared electrons. Create a molecule of fluorine,
F2. Take a snapshot of this molecule and add it to the document. (Be sure to label each molecule you add.)
�
✏️ What is the Lewis diagram for fluorine, F2? (Note: Just fill in the dash, not the dots.)
F
F
5. Think and discuss: How is the formation of covalent bonds similar to kids sharing markers? How is it
different? If possible, discuss your answer with your classmates and teacher.
Activity B:
Building
molecules
Get the Gizmo ready:
● Click Reset.
● Turn off Show Lewis diagram.
● Select Oxygen.
Question: How do atoms share more than one pair of electrons?
1. Observe: Like fluorine and most other elements, oxygen atoms are most stable with a full complement of
eight valence electrons.
A. How many valence electrons does each oxygen atom have now?
\
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B. How many more electrons does each oxygen atom need to be stable?
2. Form a bond: Drag electrons back and forth until the molecule of oxygen (O2) is stable. Click Check to
confirm your molecule is stable. Take a snapshot and paste the image into your document (don’t forget to
label it “O2”).
Turn on Highlight shared electrons. How many pairs of shared electrons
are there in a stable molecule of oxygen?
3. ✏️ Draw a diagram: Draw a Lewis diagram of the oxygen molecule in the space below at left. To check your
work, turn on Show Lewis diagram. Draw the correct diagram on the right. (In these diagrams, just fill in
the dashes. Don't worry about the electron dots.)
✏️ Hand draw in this space or click here to select EDIT to use the drawing tool.
Practice diagram:
O
O
Actual:
O
O
4. Practice: Create covalent bonds and stable molecules for the remaining substances.
� Take a snapshot of each completed molecule and add it to your document.
�
✏️ Draw Lewis diagrams for each one. As above, draw the diagram on your own before checking your
work. Don't bother with drawing the individual dots, just focus on the dashes.
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✏️ Hand draw in this space or click here to select EDIT to use the drawing tool.
H
Nitrogen
N
N
Ammonia
Chlorine
Cl
H
Cl
H
H
Methane
Water
N
H
O
H
C
H
H
H
O
Carbon dioxide
O
C
O
Formaldehyde
H
C
H
5. Count: Review the Lewis diagrams you drew above. Note that each element tends to form a certain
number of chemical bonds. This value is the valence of the element.
For each element in the table below, use the Gizmo to find the number of valence electrons and the list the
valence based on the Lewis diagram. Then find the sum of these numbers.
Element
Symbol
Fluorine
F
Hydrogen
H
Oxygen
O
Nitrogen
N
Chlorine
Cl
Carbon
C
# of valence
electrons
Valence
Sum
6. Make a rule: If you knew the number of valence electrons in a nonmetal atom, how would you determine
the valence of the element? (Hint: Ignore hydrogen for now.)
7. Analyze: The first shell can hold a maximum of two electrons. How does this explain the valence of
hydrogen?
8. Apply: Selenium has six valence electrons. What is the valence of selenium? 8
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9. Think and discuss: The last column of the periodic table contains the noble gases, elements that do not
easily form chemical bonds.
Why don’t these gases tend to form chemical bonds?
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